Automatic control for carburetor throttle valves



Nov. 7, 1950 H. s. BROWN ETAL ?952923 AUTQMATIC CONTROL FOR CARBURETOR THROTTLE VALVES 3 Sheets-Sheet Original Filed Sept. 10, 1949 Wernsrfifirmsimzzg Z1 Yezchez'zbach AUTOMATIC CONTROL FOR CARBURETOR THROTTLE VALVES Original Filed Sept. 10, 1949 Nov. 7, 1950 H. s. BROWN ETAL 3 Sheets-Sheet 2 4m HZ. w LE W Sh MDEmm if. H MM? fi p s 2 WJ Nov. 7, 1950 H. 5. BROWN ETAL 2,529,243

AUTOMATIC CONTROL FOR CARBURETOR THROTTLE VALVES Original Filed Sept. 10, 1949 3 Sheets-Sheet 3 Hugh .51 Brawn 47 Werner Eflrmsiranq Jasppiz KXHE'Z Chen baa/7 Patented Nov. 7, 1950 AUTOMATIC CONTROL FOR CARBURETOR THROTTLE VALVES Hugh S. Brown, Wauwatosa, and Werner E. Armstrong and Joseph V. Reichenbach, Milwaukee, Wis., assignors to Briggs & Stratton Corporation, Milwaukee, Wis., a corporation of Delaware Original application September 10, 1949, Serial No. 114,982. Divided and this application July 31, 1950, Serial No. 176,881

4 Claims. 1

v This application is a division of our copending application, Serial No. 114,982, filed September 10, 1949, which claims the general combination of the carburetor and is related to our copending application, Serial No. 176,882, filed July 31, 1950, which covers the novel features of the carburetor throttle valve.

The present invention relates to the means for adjusting the throttle valve by an engine speed responsive governor, and has as its purpose to provide an improved and simplified manner of connecting the throttle valve with the governor driven motion producing linkage by which the imposition of side thrust upon the valve is precluded and manual setting of the governor mechanism is facilitated.

With the above and other objects in view which will appear as the description proceeds, this invention resides in the novel construction, combination and arrangement of parts substantially as hereinafter described, and more particularly defined by the appended claims, it being understood that such changes in the precise embodiment of the hereindisclosed invention may be made as come within the scope of the claims.

The accompanying drawings illustrate several complete examples of the physical embodiments of the invention constructed in accordance with the best modes so far devised for the practical application of the principles thereof, and in which:

Figure 1 is a perspective view showing a portion of a one cylinder internal combustion engine with the carburetor embodying this invention applied thereto, the air cleaner being omitted in this view;

Figure 2 is a top plan view of the carburetor, again with the air cleaner removed;

Figure 3 is a side view of the carburetor;

Figure 4 is a cross sectional view taken through Figure 3 on the plane of the line 4|;

' Figure 5 is a side view similar to Figure 3 but illustrating the manner in which remote control is provided for the throttle;

Figure 6 is a fragmentary side view showing a slightly modified form of remote control; and

Figure 7 is a detail sectional view through Figure 6 on the plane of the line 1-1.

Referring now particularly to the accompanying drawings in which lik numerals indicate like parts throughout the several views, the numeral 5 indicates generally the. carburetor described and claimed in the aforesaid parent application, Serial Number 114,982. The body 6 of the carburetor is an elongated hollow die casting having a longitudinally extending bore 1 opening 00 one 2 end of the body and an attaching flange 8 at said end. The attaching flange provides means by which the body is securable to the cylinder 9 of an engine.

The engine, of course, may be of any desired construction with its cylinder either vertical as shown or horizontali In any event when the carburetor is secured in place on the cylinder the mouth of its bore I which provides a mixture or induction passage opens to the intake port ill of the engine and the body 6 projects horizontally outwardly from the cylinder as a rigid load carrying member.

At its outer end portion the body has a downwardly projecting bracket ll having a flat bottom wall II. Thi bracket serves to strengthen the body and its fiat bottom wall provides a gasket flange to which a fuel tank I3 is secured with a gasket H interposed therebetween. The top and bottom walls of the tank are substantially flat and parallel, and the top wall thereof is reinforced by a plate 15 into which the mounting screws are threaded.

The extreme outer end portion of the tubular body has an upstanding hollow boss [6 formed thereon, the hollow interior of which defines a well communicating with the bore 1 through an air inlet opening it in the bottom thereof. A flange H at the top of this boss provides a base upon which a conventional air cleaner I8 is seated, the air cleaner being held in place in the customary manner by a tension screw I9 extending downwardly through the center thereof and threaded into the body. Thus with the carburetor mounted on the engine cylinder in the manner described engine suction draws air into the outer end of the mixture passage provided by the bore 1. Engine suction also draws fuel from the tank into the mixture passage through a jet (not shown) in amounts governed by the adjustment of a needle valve 20.

Attention is directed to the fact that the head of the needle valve adjusting screw is accessible at the side of the body above the'fuel tank and that the axis of the screw lies in a plane parallel with the top wall of the tank and substantially perpendicular to the axis of the mixture passage 1. The advantage of this location of the needle valve adjusting screw will be apparent hereinafter.

Adjacent to the point at which the fuel jet opens into the mixture passage the body 6 has an upright cylindrical valve socket Or well 2| intersecting its bore I and opening to the top of a boss 22 formed on the body. Seated in the socket is a barrel-like throttle valve 23 which has a head 24 overlying the boss 22. Since the valve turns on a vertical axis there is little chance of its binding in the socket which is important from the standpoint of automatic control as will be hereinafter brought out.

Since the body 6 constitutes a load carrying member it is desirable to provide as much reinforcement therefor as possible. To this end side ribs 25, a top rib 25 and a bottom rib 21 are formed along the length of the body to merge with the attaching flange 8. The top rib 26 is interrupted by the boss 22 which defines the top of the valve socket, and at one side of this boss the rib 26 is enlarged to provide a stop 28 and at the other side thereof the rib 25 is undercut to provide an overhanging ledge 29. This ledge 29 coacts with a segment-like flange 30 integral with the head 24 of the valve to hold the valve in the socket except when the valve is turned beyond one of its normal limits of rotation.

One of these limits of rotation is defined by the engagement of a radial arm-3| projecting from the head of the valve with one side of the stop 28. The position thus defined is the full open position of the valve. The other or idling position is defined by the engagement of a screw 32 with the stop 28, the screw 32 being adjustably threaded in another arm 33 extending radially from the head of the valve. A spring 34 encircling the screw 32 bears against the underside of its head and thus frictionally holds the screw in adjusted position.

As will be readily apparent the adjustability of the screw 32 enables the valve to be turned far enough in a counterclockwise direction (as viewed in Figure 2) to bring the segment-like flange 30 clear of the overhanging ledge 29. This manner of securing the valve in position is particularly advantageous in assembly since it merely requires dropping the valve into its socket and advancing the screw 32 into proper position.

Inasmuch as the carburetor of this invention is designed especially for use in small portable single cylinder engines which often are called upon to operate entirely unattended, it is desirable to provide an automatic control for the throttle valve to thereby coordinate the speed of the engine with the load imposed thereon. Such controls, of course, are not new in themselves, Patent No. 1,660,079 issued to Perry E. Mack, being an example thereof.

As in the aforesaid patent the control here. employed also utilizes a vane 35 mounted to be influenced by air pressure emanating from the ventilating fan blades 36 on the fly wheel 31 of the engine, this air blast being directed and guided by a shroud 38. The blade 35 which is secured toa hinged actuator arm 39 is adapted to be moved toward the right in Figure 1 by the air blast. Such movement of the blade and arm 39 is imparted to the throttle valve through a wire link 40 to rotate the valve toward its idling position and thus slow up the engine whenever the engine speeds up due to a diminishing load.

Though, as will be readily appreciated, the end of the wire 40 could be hooked directly to some part of the throttle valve, to simplif the die casting thereof a stamped sheet metal attaching clip 4| is provided for this purpose. This clip is conveniently held in place b the idle adjusting screw 32. To this end the clip has a part 42 which overlies and embraces the Y 4 arm 33 on the valve where it is held by the screw 32 and its holding spring 34'.

The response of the governor vane 35 to air pressure is opposed by a spring 43, the tension of which determines the speed at which the engine will run. The manner in which this spring is adjusted is one of the features of this invention and is'designed with a view toward achieving utmost simplicity and convenience. One end of the spring is hooked into a loop 44 formed in the wire link 4|]. Its other end is hooked onto a lever 45 pivoted to swing about a horizontal axis toward and from the spring 43. A screw 46 provides the pivot for the lever 45 and also clamps a stamping 41 to the side of a boss 43 which forms part of the body bracket II. This detail is shown in Figure 4.

The stamping 4'1 has an arcuate part 49 bent back to form an inclined cam surface across which the free end of the lever 45 swings so that a screw 50 threaded into the lever and bearing against the inclined cam 49 increases the tension on the spring 43 as the screw 50 is threaded farther into the lever 43. The screw 50 thus constitutes the speed adjusting screw, and to hold the same against accidental displacement from adjustment a compression spring is interposed between its head and the outer face of the lever 45.

Since the head of the screw 50 faces in the same direction as the head of the needle valve screw and since these screws are. parallel and relatively closely adjacent to each other, adjustment of the needle valve and the tension of the spring 43 to determine the speed at which the engine will run may be simply and conveniently accomplished.

It is to be noted that whereas the throttle valve is moved in one direction by the governor mechanism and in the other direction by the spring 43, there are no forces acting upon the valve in a way which could cause it to bind in its socket. The spring is tensioned directly between the governor arm 39 and the adjustable lever 45 and motion of the governor arm 33 produced either by the spring or the air blast is translated into rotation of the throttle valve through the link 40. The spring force is thus not carried through the throttle valve to the 50 governor.

If the pull of the spring in anywise imposes a side thrust upon the valve, as is common in carburetor controls of the past, the resulting tendency to tilt the valve in its socket causes it to stick or bind and thereby render the automatic control of the engine unreliable.

This particular manner of adjustably anchoring the spring 43 also lends itself well to remote control of the spring tension and consequently the governor maintained engine speed. Thus as shown in Figure 5, by-removal of the screw 50 and connection of a remote control wire 5| to the lever 45 it is possible to quickly and easily adjust the lever and consequently the tension oi.

the spring. The wire 5| slides in a flexible sheath 7 here shown the lever 451s replaced by a longer lever 54 and the arcuate part 49' of the stamping 41' instead oi being bent down to form a cam is left flat to have the lever 54 slide thereacross as it swings about its pivot.

A spring tensioned friction clamp 55 carried by the lever 54 engages the other side of the arcuate arm 49' as shown in Figure 7 to frictionally hold the lever in any adjusted position. The lever 54 is, of course, movable back and forth in any suitable manner either directly or by means of a remote control wire (not shown).

From the foregoing description taken in connection with the accompanying drawings it will be readily apparent to those skilled in the art that this invention provides a highly reliable automatic governor mechanism for the carburetors of small single cylinder internal combustion engines, since it affords maximum assurance against the imposition of side thrust upon the throttle valve, and that this objective is attained with simple readily adjusted mechanism.

What we claim as our invention is:

1. In a carburetor for internal combustion engines equipped with a governor for controlling engine speed by adjusting the carburetor throttle valve. and having a speed responsive motion producing element constrained to movement in a fixed plane, the carburetor having an axially straight induction passage and the throttle valve being mounted to turn on an axis intersecting that of the induction passage: means mounting the carburetor with the axis of its induction passage parallel to the plane of movement of the motion producing element; a wire link having one end attached to the throttle valve eccentrically to its axis of rotation and its other end attached to the motion producing element, said wire link having a loop medially of its ends; a pivoted lever mounted to swing about a fixed pivot towards and from the loop in the wire link and in a plane substantially parallel to the axis of the induction passage and in line with the plane of movement of the speed responsive motion producing element; adjustable stop means for limiting swinging movement of the pivoted lever towards the loop in the wire link; and a coiled tension spring having one end attached to said pivoted lever and its other end attached to the loop in the wire link so that the end portion of the wire link between its loop and its connection with the motion producing element of the governor carries the spring force to the govergcrmout imposing side thrust upon the throt- 2. In a carburetor, the governor structure set forth in claim 1 further characterized by the fact that the adjustable stop comprises an inclined cam surface across which the lever swings, and a screw threaded in the lever and reacting against the inclined cam surface to impart movement to the lever by adjustment of the screw.

3. In a carburetor, the governor structure set forth in claim 1 further characterized by the fact that the lever has means thereon for the reception of a remote control wire, said means being so located that a pull exerted upon the remote control wire is in line with the axis of the coiled tension spring.

4. In a carburetor for internal combustion engines equipped with a governor for controlling engine speed by adjusting the carburetor throttle valve, and including a speed responsive motion producing element constrained to movement in a fixed plane: a motion transmitting link having one end attached to said speed responsive motion producing element and its other end connected with the throttle valve; a coiled tension spring having one end connected to the link medially of the ends of the link; a pivoted lever to which the other end of the coiled tension spring is attached, said pivoted lever being constrained to swing in said fixed plane toward and from the speed responsive motion producing element; and adjustable stop means for limiting swinging movement: of said lever toward the speed responsive motion producing element, said adjustable stop means including a screw rotatable on an axis normal to said fixed plane with its head at one side of the carburetor body.

HUGH S. BROWN. WERNER E. ARMSTRONG. JOSEPH V. REICHEN'BACH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date" 1,201,821 Hobart Oct. 17, 1916 1,331,161 Londt Feb. 17, 1920 1,720,561 Maier et a1 July 9, 1929 1,774,080 Brandl et al. Aug. 26, 1930 1,843,960 Sticelber Feb. 9, 1932 2,019,578 Noltein Nov. 5, 1935 2,452,208 Reger Oct. 26, 1948 2,468,361 Elleman Apr. 26, 1949 

